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Old 4th April 2014, 10:10 PM   #4841
goo is offline goo  Norway
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Join Date: Jul 2011
Quote:
Originally Posted by Shortrope View Post
Just how much of an improvement is the Lifepo4 over an SLA??
Is size and weight the only advantage?
Is it worth the extra cost and complicated electronics?
I'd love to hear folk's experiences before I consider going that way.
I have used 2 x 9 Ah lifepo4 in my new boominator and love it, it charges faster than SLAs from previous portable builds, holds its voltage when not in use, it weighs less and lasts longer.

I always have had problems with keeping the SLA batteries fresh, they degrade and eventually you can not charge them full. You really need to be careful with them.

It seems that the Lifepo4 handle much more abuse.

NB I just had Lifepo4 for a few cycles so off course i might be wrong...
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Old 5th April 2014, 12:18 AM   #4842
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Default SLA vs Li-ion vs LiFePO4

Advantages LiFePo4
-Weight, 40-50% of a SLA battery with the same capacity
-Can be fully discharged, SLA has to have 10-15% left
-Safety, as euforia said: no toxic metals. Also thermal runaway is impossible and it's chemically stable so almost no chance of explosion as opposed to li-ion
-High (dis)charge rates
-High and stable voltage without exceeding the amps' limit.
-High cyclerates (often >2000) and no memory effect.
-Low selfdischarge, can be left alone a long time without losing much capacity
-Can keep it's capacity in a wide temperature range
-Can be UN38.3 certified, although it costs money, and is allowed to be shipped

Disadvantage LiFePO4:
-Cost, but if you take the high cyclerate into account it's even cheaper than SLA.
-Not a lot of manufacturers and therefore hardly available, but (I think) it will come with the time.
-Lower Wh/L compared to li-ion

Advantages SLA:
-Cheap, in particular the 7.2ah ones because of the high production rate
-Safe, not as safe as LiFePO4 but a lot safer than li-ion
-Easy to charge, wide range of chargers available
-High and relatively stable voltage without exceeding the amps' limit

Disadvantages SLA:
-low deepcharge cyclerate (+/-300)
-weight (2.5kg for 7.2ah)
-easy to damage, contains no BMS/PCM and can thus be deepcharged. Deepcharge will create irreversible damage. Can be prevented with a deep-charge protection PCB.

Advantages li-ion
-Very high discharge rates, therefore used a lot in the RC world
-Lowest weight of all.
-Price and cycle life are in between LiFePO4 and SLA
-Relativily easy to charge, a lot of balance chargers are readily available on Ebay for example.
-Available in a lot of shapes: prismatic, cylindrical and pouch cells
-High Wh/L

Disadvantages li-ion:
-Will explode eventually. The risk is really low, but it is there
-Low nominal voltage compared to the other batteries.
-Can't be UN38.3 certified and therefore not allowed to be shipped in high capacities

Probably missed quite some things, and correct if i'm wrong
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Old 5th April 2014, 09:12 AM   #4843
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Brillant!....I think that covers it!!
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Old 5th April 2014, 10:07 AM   #4844
WesleyK is offline WesleyK  Netherlands
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Join Date: Oct 2012
Quote:
Originally Posted by lutkeveld View Post
Advantages LiFePo4
-Weight, 40-50% of a SLA battery with the same capacity
-Can be fully discharged, SLA has to have 10-15% left
-Safety, as euforia said: no toxic metals. Also thermal runaway is impossible and it's chemically stable so almost no chance of explosion as opposed to li-ion
-High (dis)charge rates
-High and stable voltage without exceeding the amps' limit.
-High cyclerates (often >2000) and no memory effect.
-Low selfdischarge, can be left alone a long time without losing much capacity
-Can keep it's capacity in a wide temperature range
-Can be UN38.3 certified, although it costs money, and is allowed to be shipped

Disadvantage LiFePO4:
-Cost, but if you take the high cyclerate into account it's even cheaper than SLA.
-Not a lot of manufacturers and therefore hardly available, but (I think) it will come with the time.
-Lower Wh/L compared to li-ion

Advantages SLA:
-Cheap, in particular the 7.2ah ones because of the high production rate
-Safe, not as safe as LiFePO4 but a lot safer than li-ion
-Easy to charge, wide range of chargers available
-High and relatively stable voltage without exceeding the amps' limit

Disadvantages SLA:
-low deepcharge cyclerate (+/-300)
-weight (2.5kg for 7.2ah)
-easy to damage, contains no BMS/PCM and can thus be deepcharged. Deepcharge will create irreversible damage. Can be prevented with a deep-charge protection PCB.

Advantages li-ion
-Very high discharge rates, therefore used a lot in the RC world
-Lowest weight of all.
-Price and cycle life are in between LiFePO4 and SLA
-Relativily easy to charge, a lot of balance chargers are readily available on Ebay for example.
-Available in a lot of shapes: prismatic, cylindrical and pouch cells
-High Wh/L

Disadvantages li-ion:
-Will explode eventually. The risk is really low, but it is there
-Low nominal voltage compared to the other batteries.
-Can't be UN38.3 certified and therefore not allowed to be shipped in high capacities

Probably missed quite some things, and correct if i'm wrong
Nice list, extremely useful for beginners .

One little note though:
SLA still is the cheapest and easiest battery to use. It's by far the easiest battery to charge and to protect. Just add a under voltage protection and a fuse and you're ready. No need for over voltage protection(as long as you have a SLA charger), balancing and measuring cell voltages. For a beginner this is still the way to go. High capacity, low price, easy to easy.
I would never recommend a Li-ion pack for a beginner, you'll really need to know what you're talking about before you can safely use these batteries. They are great capacity/weight and capacity/liters but dangerous in the wrong hands. I think this is missing as a disadvantage in your list, for both the Li-ion and LiFePO4. These batteries needs proper protection, over discharge, overcharge, overcurrent and preferably balancing. This means that with Li-ion or LiFePO4 you can't just add your system to the + and - pole, but a PCM or BMS is needed with wires connected to each cell. Quite complicated for a beginner. Another problem is that you'll need either spot welded tabs or a battery holder as you can't solder directly to the cells (this will permanently damage them). Another small note: SLA batteries are easy to damage when they are deep discharged, but the same applies to Li-ion and LiFePO, if discharged too far, they will permanently damage. LiFePO4 suffers the least from this problem though, as they can be 100% discharged and still last quite a while they do last longer though, with a d.o.d. <100%. With Li-ion their rated cycle rate can only be achieved by not fully charging them and not fully discharging them (usually 4.1V max charge and 3.5-3.6V max discharge).

Edit:
Oh and then there are all those fake 18650 li-ion cells and LiFePO4 cells. Be careful with this. If it is to good to be true, it probably is . There are no fake SLA cells as far as I know, but you do have to be careful with not buying them brand new.

Last edited by WesleyK; 5th April 2014 at 10:30 AM.
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Old 5th April 2014, 02:10 PM   #4845
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Join Date: May 2013
They can all be damaged by deepcharge indeed, it's just that SLA batteries are bare cells and are often used without any protection. LiFePO4 and Li-ion often have a PCM/BMS or low-voltage alarm, that's common practice and regarded as neccesary.

IMO SLA's are not the easiest to charge, RC lithium packs are. Chargers are almost all based on the same standard, CC/CV till 4.2v is reached. Higher quality ones will top the pack off, although this isn't strictly necessary but it will leverage the full potential of the battery. As you say, DIY battery packs are quite tricky. Not recommended for beginners, but the basics can be learned quite fast.

I'm also not aware of any 'fake' SLA's, but there is ofcourse a difference between a known and trusted manufacturer and a low quality cheap one.

And does anyone have experience, or a link to a good source, about charging a 3S pack? I see a lot of packs that charge PCM (so no balancing) what is the short- and longterm impact on the battery?
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Old 5th April 2014, 02:20 PM   #4846
WesleyK is offline WesleyK  Netherlands
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Join Date: Oct 2012
Yep but while a 12V SLA can be used without protection(but with common sense), you should absolutely never use li-ion without protection.

RC packs are easy, but they are also one of the most dangerous li-ion packs available. I've seen one catch fire myself, not good . With SLA that won't happen. Another problem with them is that you have to store them at 3.7-3.8V when not using them, otherwise they'll "puff"

Last edited by WesleyK; 5th April 2014 at 02:28 PM.
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Old 5th April 2014, 07:03 PM   #4847
Silas K is offline Silas K  Denmark
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Join Date: Mar 2014
Quote:
Originally Posted by Saturnus View Post
I'd hold on with making a Boominator MINI/MICRO right now. There'll be a few changes coming.
What kind og changes will that be?

Just ordered the aurasound ns525
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Old 6th April 2014, 12:24 PM   #4848
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Join Date: Mar 2011
Quote:
Originally Posted by Silas K View Post
What kind og changes will that be?

Just ordered the aurasound ns525
I think they are talking about "The new Mini" - the one with monacor sp60 woofers (names are so confusing, just like Apple's "The new iPad" ).

There shouldn't be any changes regarding the old mini using aurasound ns525. Just follow the thread on speakerplans.com and you should be fine.
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Old 6th April 2014, 01:52 PM   #4849
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Can someone make a list with different pro's and cons for different solar panel types like I did with the batteries? Most guides are not applicable to portable equipement, more for on top of your house etc.
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Old 6th April 2014, 04:48 PM   #4850
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Quote:
Originally Posted by WesleyK View Post
Another problem with them is that you have to store them at 3.7-3.8V when not using them, otherwise they'll "puff"
Even if this might be true for long term storage, why should they "puff", when storaged fully charged? The only disadvantage i know, is the recombination rate on cycling when stored fully charged.

Every "semipro" charger will offer a "storage-charge", where they will charge/discharge to 3.6-3.8V. (Exact voltage is noted in the cells datasheet)
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